- Structure-Guided Regulation in the Enantioselectivity of an Epoxide Hydrolase to Produce Enantiomeric Monosubstituted Epoxides and Vicinal Diols via Kinetic Resolution
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Structure-guided microtuning of an Aspergillus usamii epoxide hydrolase was executed. One mutant, A214C/A250I, displayed a 12.6-fold enhanced enantiomeric ratio (E = 202) toward rac-styrene oxide, achieving its nearly perfect kinetic resolution at 0.8 M in pure water or 1.6 M in n-hexanol/water. Several other beneficial mutants also displayed significantly improved E values, offering promising biocatalysts to access 19 structurally diverse chiral monosubstituted epoxides (97.1 - ≥ 99% ees) and vicinal diols (56.2-98.0% eep) with high yields.
- Hou, Xiao-Dong,Hu, Bo-Chun,Hu, Die,Lei, Yu-Qing,Rao, Yi-Jian,Wu, Min-Chen,Zhang, Dong
-
supporting information
p. 1757 - 1761
(2022/03/16)
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- Method for synthesizing chiral 1,2-diol compound
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The invention relates to a method for synthesizing a chiral 1,2-diol compound, which comprises the following steps: sequentially adding a cobalt catalyst, a ligand, alpha-hydroxy ketone, an organic solvent and silane into a reaction system at 20-30 DEG C in a nitrogen atmosphere, then stirring the mixture, and carrying out column chromatography separation on the obtained product to obtain the chiral 1,2-diol compound. The high-yield cobalt catalyst in the earth crust is used, meanwhile, cheap silane (PMHS, 500 g/298 yuan) is used as a reducing agent, the asymmetric reduction reaction of alpha-hydroxy ketone can be efficiently achieved under the mild condition, and the chiral 1,2-diol compound with high yield and optical activity is obtained. Moreover, through the creative labor of the inventor, the reaction yield can reach 99%, and meanwhile, the content of the target product in the generated reaction product is 99% (namely, the yield is 99%, 99% ee).
- -
-
Paragraph 0027; 0041-0044
(2021/07/21)
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- Lewis Base Catalyzed Dioxygenation of Olefins with Hypervalent Iodine Reagents
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1,2-Diols are extremely useful building blocks in organic synthesis. Hypervalent iodine reagents are useful for the vicinal dihydroxylation of olefins to give 1,2-diols under metal-free conditions, but strongly acidic promoters are often required. Herein, we report a catalytic vicinal dioxygenation of olefins with hypervalent iodine reagents using Lewis bases as catalysts. The conditions are mild and compatible with various functional groups.
- Pan, Liangkun,Ke, Zhihai,Yeung, Ying-Yeung
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supporting information
p. 8174 - 8178
(2021/10/25)
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- Catalytic Diastereo- and Enantioconvergent Synthesis of Vicinal Diamines from Diols through Borrowing Hydrogen
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We present herein an unprecedented diastereoconvergent synthesis of vicinal diamines from diols through an economical, redox-neutral process. Under cooperative ruthenium and Lewis acid catalysis, readily available anilines and 1,2-diols (as a mixture of diastereomers) couple to forge two C?N bonds in an efficient and diastereoselective fashion. By identifying an effective chiral iridium/phosphoric acid co-catalyzed procedure, the first enantioconvergent double amination of racemic 1,2-diols has also been achieved, resulting in a practical access to highly valuable enantioenriched vicinal diamines.
- Feng, Wei,Gao, Taotao,Lau, Kai Kiat,Lin, Yamei,Pan, Hui-Jie,Yang, Binmiao,Zhao, Yu
-
supporting information
p. 18599 - 18604
(2021/08/09)
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- Iodine-Initiated Dioxygenation of Aryl Alkenes Using tert-Butylhydroperoxides and Water: A Route to Vicinal Diols and Bisperoxides
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An environment-friendly and efficient dioxygenation of aryl alkenes for the construction of vicinal diols has been developed in water with iodine as the catalyst and tert-butylhydroperoxides (TBHPs) as the oxidant. The protocol was efficient, sustainable, and operationally simple. Detailed mechanistic studies indicated that one of the hydroxyl groups is derived from water and the other one is derived from TBHP. Additionally, the bisperoxides could be obtained in good yields with iodine as the catalyst, Na2CO3 as the additive, and propylene carbonate as the solvent, instead.
- Gao, Xiaofang,Lin, Jiani,Zhang, Li,Lou, Xinyao,Guo, Guanghui,Peng, Na,Xu, Huan,Liu, Yi
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p. 15469 - 15480
(2021/11/16)
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- Manipulating regioselectivity of an epoxide hydrolase for single enzymatic synthesis of (: R)-1,2-diols from racemic epoxides
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Both the activity and regioselectivity of Phaseolus vulgaris epoxide hydrolase were remarkably improved via reshaping two substrate tunnels based on rational design. The elegant one-step enantioconvergent hydrolysis of seven rac-epoxides was achieved by single mutants, allowing green and efficient access to valuable (R)-1,2 diols with high eep (90.1-98.3%) and yields.
- Hu, Die,Zong, Xun-Cheng,Xue, Feng,Li, Chuang,Hu, Bo-Chun,Wu, Min-Chen
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supporting information
p. 2799 - 2802
(2020/03/13)
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- Reprogramming Epoxide Hydrolase to Improve Enantioconvergence in Hydrolysis of Styrene Oxide Scaffolds
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Enantioconvergent hydrolysis by epoxide hydrolase is a promising method for the synthesis of important vicinal diols. However, the poor regioselectivity of the naturally occurring enzymes results in low enantioconvergence in the enzymatic hydrolysis of styrene oxides. Herein, modulated residue No. 263 was redesigned based on structural information and a smart variant library was constructed by site-directed modification using an “optimized amino acid alphabet” to improve the regioselectivity of epoxide hydrolase from Vigna radiata (VrEH2). The regioselectivity coefficient (r) of variant M263Q for the R-isomer of meta-substituted styrene oxides was improved 40–63-fold, and variant M263V also exhibited higher regioselectivity towards the R-isomer of para-substituted styrene oxides compared with the wild type, which resulted in improved enantioconvergence in hydrolysis of styrene oxide scaffolds. Structural insight showed the crucial role of residue No. 263 in modulating the substrate binding conformation by altering the binding surroundings. Furthermore, increased differences in the attacking distance between nucleophilic residue Asp101 and the two carbon atoms of the epoxide ring provided evidence for improved regioselectivity. Several high-value vicinal diols were readily synthesized (>88% yield, 90%–98% ee) by enantioconvergent hydrolysis using the reprogrammed variants. These findings provide a successful strategy for enhancing the enantioconvergence of native epoxide hydrolases through key single-site mutation and more powerful enzyme tools for the enantioconvergent hydrolysis of styrene oxide scaffolds into single (R)-enantiomers of chiral vicinal diols. (Figure presented.).
- Li, Fu-Long,Qiu, Yan-Yan,Zheng, Yu-Cong,Chen, Fei-Fei,Kong, Xu–Dong,Xu, Jian-He,Yu, Hui-Lei
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p. 4699 - 4706
(2020/09/21)
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- Visible light induced redox neutral fragmentation of 1,2-diol derivatives
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A homogeneous, redox-neutral photo fragmentation of diol derivatives was developed. Under photo/hydrogen atom transfer (HAT) dual catalysis, diol derivatives such as lignin model compounds and diol monoesters undergo selective β C(sp3)-O bond cleavage to afford ketones, phenols and acids effectively.
- Chen, Kang,Schwarz, Johanna,Karl, Tobias A.,Chatterjee, Anamitra,K?nig, Burkhard
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supporting information
p. 13144 - 13147
(2019/11/11)
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- Asymmetric ring opening of racemic epoxides for enantioselective synthesis of (S)-β-amino alcohols by a cofactor self-sufficient cascade biocatalysis system
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A novel one-pot epoxide hydrolase/alcohol dehydrogenase/transaminase cascade process for the asymmetric ring opening of racemic epoxides to enantiopure β-amino alcohols is reported. The product (S)-β-amino alcohols were obtained in 97-99% ee and 79-99% conversion from readily available racemic epoxides.
- Zhang, Jian-Dong,Yang, Xiao-Xiao,Jia, Qiao,Zhao, Jian-Wei,Gao, Li-Li,Gao, When-Chao,Chang, Hong-Hong,Wei, Wen-Long,Xu, Jian-He
-
-
- Exploiting Designed Oxidase-Peroxygenase Mutual Benefit System for Asymmetric Cascade Reactions
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A unique P450 monooxygenase-peroxygenase mutual benefit system was designed as the core element in the construction of a biocatalytic cascade reaction sequence leading from 3-phenyl propionic acid to (R)-phenyl glycol. In this system, P450 monooxygenase (P450-BM3) and P450 peroxygenase (OleTJE) not only function as catalysts for the crucial initial reactions, they also ensure an internal in situ H2O2 recycle mechanism that avoids its accumulation and thus prevents possible toxic effects. By directed evolution of P450-BM3 as the catalyst in the enantioselective epoxidation of the styrene-intermediate, formed from 3-phenyl propionic acid, and the epoxide hydrolase ANEH for final hydrolytic ring opening, (R)-phenyl glycol and 9 derivatives thereof were synthesized from the respective carboxylic acids in one-pot processes with high enantioselectivity.
- Yu, Da,Wang, Jian-Bo,Reetz, Manfred T.
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-
- Exploiting Designed Oxidase-Peroxygenase Mutual Benefit System for Asymmetric Cascade Reactions
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A unique P450 monooxygenase-peroxygenase mutual benefit system was designed as the core element in the construction of a biocatalytic cascade reaction sequence leading from 3-phenyl propionic acid to (R)-phenyl glycol. In this system, P450 monooxygenase (P450-BM3) and P450 peroxygenase (OleTJE) not only function as catalysts for the crucial initial reactions, they also ensure an internal in situ H2O2 recycle mechanism that avoids its accumulation and thus prevents possible toxic effects. By directed evolution of P450-BM3 as the catalyst in the enantioselective epoxidation of the styrene-intermediate, formed from 3-phenyl propionic acid, and the epoxide hydrolase ANEH for final hydrolytic ring opening, (R)-phenyl glycol and 9 derivatives thereof were synthesized from the respective carboxylic acids in one-pot processes with high enantioselectivity.
- Yu, Da,Wang, Jian-Bo,Reetz, Manfred T.
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p. 5655 - 5658
(2019/04/17)
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- Bifunctional organocatalysts for the conversion of CO2, epoxides and aryl amines to 3-aryl-2-oxazolidinones
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A route to synthesize 3-aryl-2-oxazolidinones is developed, which is achieved through a three component reaction between CO2, aryl amines, and epoxides with a binary organocatalytic system composed of organocatalysts and DBU (1,8-diazabicyclo[5.4.0]undec-7-ene). The method allows wide scopes of epoxide and aryl amine substrates with various functional groups under mild reaction conditions. The control experiments indicate that a cyclic carbonate is formed via cycloaddition of epoxides with CO2, which further reacts with the β-amino alcohol originating from epoxides and aryl amines, resulting in the formation of 3-aryl-2-oxazolidinones finally.
- Xie, Ya-Fei,Guo, Cheng,Shi, Lei,Peng, Bang-Hua,Liu, Ning
-
supporting information
p. 3497 - 3506
(2019/04/14)
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- Kinetic Resolution of 1,2-Diols via NHC-Catalyzed Site-Selective Esterification
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A kinetic resolution of 1,2-diols bearing both a secondary and a primary alcohol motif through an N-heterocyclic carbene-catalyzed oxidative acylation reaction has been developed. A site- and enantioselective esterification reaction is involved for this process. Both the monoacylated diols obtained and the remaining enantioenriched 1,2-diols are versatile building blocks for the preparation of functional molecules with proven biological activities.
- Liu, Bin,Yan, Jiekuan,Huang, Ruoyan,Wang, Weihong,Jin, Zhichao,Zanoni, Giuseppe,Zheng, Pengcheng,Yang, Song,Chi, Yonggui Robin
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supporting information
p. 3447 - 3450
(2018/06/26)
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- Chiral Ion-Pair Organocatalyst-Promoted Efficient Enantio-selective Reduction of α-Hydroxy Ketones
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The enantioselective reduction of α-hydroxy ketones with catecholborane has been developed employing 5 mol% of an 1,1′-bi-2-naphthol (BINOL)-derived ion-pair organocatalyst. This methodology provides a straightforward access to the corresponding aromatic 1,2-diols in high yields (up to 90%) with excellent enantioselectivities (up to 97%). Furthermore, the α-amino ketones also could be reduced with moderate ee values under mild reaction condition. (Figure presented.).
- Zhang, Yiliang,He, Li,Shi, Lei
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p. 1926 - 1931
(2018/03/27)
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- Direct, high-yielding, one-step synthesis of vic-diols from aryl alkynes
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An unprecedented, high yielding, direct, one-step synthesis of vic-diols from alkynes has been developed via metal-free, open-to-air dihydroboration with ammonia borane. The electronics of the alkyne and the reaction stoichiometry are critical for obtaining optimal yields of the 1,2-diol.
- Ramachandran, P. Veeraraghavan,Drolet, Michael P.
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supporting information
p. 967 - 970
(2018/02/14)
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- Alternatives to Phosphinooxazoline (t-BuPHOX) Ligands in the Metal-Catalyzed Hydrogenation of Minimally Functionalized Olefins and Cyclic β-Enamides
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This study presents a new series of readily accessible iridium- and rhodium-phosphite/oxazoline catalytic systems that can efficiently hydrogenate, for the first time, both minimally functionalized olefins and functionalized olefins (62 examples in total) in high enantioselectivities (ees up to >99%) and conversions. The phosphite-oxazoline ligands, which are readily available in only two synthetic steps, are derived from previous privileged 4-alkyl-2-[2-(diphenylphosphino)phenyl]-2-oxazoline (PHOX) ligands by replacing the phosphine moiety by a biaryl phosphite group and/or the introduction of a methylene spacer between the oxazoline and the phenyl ring. The modular design of the ligands has given us the opportunity not only to overcome the limitations of the iridium-PHOX catalytic systems in the hydrogenation of minimally functionalized Z-olefins and 1,1-disubstituted olefins, but also to expand their use to unfunctionalized olefins containing other challenging scaffolds (e.g., exocyclic benzofused and triaryl-substituted olefins) and also to olefins with poorly coordinative groups (e.g., α,β-unsaturated lactams, lactones, alkenylboronic esters, etc.) with enantioselectivities typically >95% ee. Moreover, both enantiomers of the hydrogenation product could be obtained by simply changing the configuration of the biaryl phosphite moiety. Remarkably, the new catalytic systems also provided excellent enantioselectivities (up to 99% ee) in the asymmetric hydrogenation of another challenging class of olefins – the functionalized cyclic β-enamides. Again, both enantiomers of the reduced amides could be obtained by changing the metal from Ir to Rh. We also demonstrated that environmentally friendly propylene carbonate can be used with no loss of enantioselectivity. Another advantage of the new ligands over the PHOX ligands is that the best ligands are derived from the affordable (S)-phenylglycinol rather than from the expensive (S)-tert-leucinol. (Figure presented.).
- Biosca, Maria,Magre, Marc,Coll, Mercè,Pàmies, Oscar,Diéguez, Montserrat
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supporting information
p. 2801 - 2814
(2017/08/23)
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- Developing a Bench-Scale Green Diboration Reaction toward Industrial Application
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We report a new methodology for the organocatalytic diboration reaction using inexpensive, sustainable, nontoxic, commercially available halogen salts. This is an educative manuscript for the transformation of laboratory scale reactions into a sustainable approach of appeal to industry.
- Farre, Albert,Briggs, Rachel,Pubill-Ulldemolins, Cristina,Bonet, Amadeu
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supporting information
p. 4775 - 4782
(2017/10/27)
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- Production Of Enantiopure alpha-Hydroxy Carboxylic Acids From Alkenes By Cascade Biocatalysis
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The invention provides compositions comprising an alkene epoxidase and a selective epoxide hydrolase, such as a recombinant microorganism comprising a first heterologous nucleic acid encoding an alkene epoxidase and a second heterologous nucleic acid encoding a selective epoxide hydrolase. Exemplary alkene epoxidases include StyAB, while exemplary selective epoxide hydrolases include epoxide hydrolases from Sphingomonas, Solanum tuberosum, or Aspergillus. The invention also provides non-toxic methods of making enantiomerically pure vicinal diols or enantiomerically pure alpha-hydroxy carboxylic acids using these compositions and microorganisms.
- -
-
Paragraph 0071-0073
(2016/05/02)
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- Enantioselective Vicinal Diacetoxylation of Alkenes under Chiral Iodine(III) Catalysis
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A procedure for the intermolecular enantioselective dioxygenation of alkenes under iodine(III) catalysis has been developed. This protocol employs Selectfluor as the terminal oxidant together with a defined C 2-symmetric aryl iodide as the organocatalyst. This enantioselective reaction proceeds under mild conditions and converts a series of terminal and internal styrenes into the corresponding vicinal diacetoxylation products with up to 96% ee.
- W?ste, Thorsten H.,Mu?iz, Kilian
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p. 816 - 827
(2016/03/15)
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- Structurally Defined Molecular Hypervalent Iodine Catalysts for Intermolecular Enantioselective Reactions
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Molecular structures of the most prominent chiral non-racemic hypervalent iodine(III) reagents to date have been elucidated for the first time. The formation of a chirally induced supramolecular scaffold based on a selective hydrogen-bonding arrangement provides an explanation for the consistently high asymmetric induction with these reagents. As an exploratory example, their scope as chiral catalysts was extended to the enantioselective dioxygenation of alkenes. A series of terminal styrenes are converted into the corresponding vicinal diacetoxylation products under mild conditions and provide the proof of principle for a truly intermolecular asymmetric alkene oxidation under iodine(I/III) catalysis.
- Haubenreisser, Stefan,W?ste, Thorsten H.,Martnez, Claudio,Ishihara, Kazuaki,Muiz, Kilian
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p. 413 - 417
(2016/01/25)
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- Transition-Metal-Free Stereospecific Cross-Coupling with Alkenylboronic Acids as Nucleophiles
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We herein report a transition-metal-free cross-coupling between secondary alkyl halides/mesylates and aryl/alkenylboronic acid, providing expedited access to a series of nonchiral/chiral coupling products in moderate to good yields. Stereospecific SN2-type coupling is developed for the first time with alkenylboronic acids as pure nucleophiles, offering an attractive alternative to the stereospecific transition-metal-catalyzed C(sp2)-C(sp3) cross-coupling.
- Li, Chengxi,Zhang, Yuanyuan,Sun, Qi,Gu, Tongnian,Peng, Henian,Tang, Wenjun
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supporting information
p. 10774 - 10777
(2016/09/09)
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- Ru-MACHO-Catalyzed Highly Chemoselective Hydrogenation of α-Keto Esters to 1,2-Diols or α-Hydroxy Esters
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A ruthenium pincer catalyst has been shown to be highly effective for the hydrogenation of a wide range of α-keto esters, affording either diols or hydroxy esters depending on the choice of reaction conditions. Strong base, high temperature, and pressure favor the formation of diols whilst the opposite is true for the hydroxy esters.
- Gao, Shaochan,Tang, Weijun,Zhang, Minghui,Wang, Chao,Xiao, Jianliang
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supporting information
p. 1748 - 1752
(2016/07/06)
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- Amine Catalysis for the Organocatalytic Diboration of Challenging Alkenes
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The generation of in situ sp2–sp3diboron adducts has revolutionised the synthesis of organoboranes. Organocatalytic diboration reactions have represented a milestone in terms of unpredictable reactivity of these adducts. However, current methodologies have limitations in terms of substrate scope, selectivity and functional group tolerance. Here a new methodology based on the use of simple amines as catalyst is reported. This methodology provides a completely selective transformation overcoming current substrate scope and functional/protecting group limitations. Mechanistic studies have been included in this report.
- Farre, Albert,Soares, Kaline,Briggs, Rachel A.,Balanta, Angelica,Benoit, David M.,Bonet, Amadeu
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supporting information
p. 17552 - 17556
(2016/11/28)
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- Highly Efficient Synthesis of Optically Pure (S)-1-phenyl-1,2-ethanediol by a Self-Sufficient Whole Cell Biocatalyst
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Terminal vicinal diols are important chiral building blocks and intermediates in organic synthesis. Reduction of α-hydroxy ketones provides a straightforward approach to access these important compounds. In this study, it has been found that asymmetric reduction of a series of α-hydroxy aromatic ketones and 1-hydroxy-2-pentanone, catalyzed by Candida magnolia carbonyl reductase (CMCR) with glucose dehydrogenase (GDH) from Bacillus subtilis for cofactor regeneration, afforded 1-aryl-1,2-ethanediols and pentane-1,2-diol, respectively, in up to 99 % ee. In order to evaluate the efficiency of the bioreduction, lyophilized recombinant Escherichia coli whole cells coexpressing CMCR and GDH genes were used as the biocatalyst and α-hydroxy acetophenone as the model substrate, and the reaction conditions, such as pH, cosolvent, the amount of biocatalyst and the presences of a cofactor (i.e., NADP+), were optimized. Under the optimized conditions (pH6, 16h), the bioreduction proceeded smoothly at 1.0 m substrate concentration without the external addition of cofactor, and the product (S)-1-phenyl-1,2-ethanediol was isolated with 90 % yield and 99 % ee. This offers a practical biocatalytic method for the preparation of these important vicinal diols. Self-sufficient catalysis! Lyophilized recombinant Escherichia coli coexpressing Candida magnolia carbonyl reductase (CMCR) and glucose dehydrogenase (GDH) genes served as an effective self-sufficient biocatalyst for the reduction of α-hydroxy acetophenones at high substrate concentrations. The products were isolated with high yield and excellent optical purity, offering a practical biocatalytic method for the preparation of vicinal diols.
- Chen, Xi,Mei, Ting,Cui, Yunfeng,Chen, Qijia,Liu, Xiangtao,Feng, Jinhui,Wu, Qiaqing,Zhu, Dunming
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p. 483 - 488
(2015/10/06)
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- Enantioselective trans-dihydroxylation of aryl olefins by cascade biocatalysis with recombinant escherichia coli coexpressing monooxygenase and epoxide hydrolase
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Cascade biocatalysis via intracellular epoxidation and hydrolysis was developed as a green and efficient method for enantioselective dihydroxylation of aryl olefins to prepare chiral vicinal diols in high ee and high yield. Escherichia coli (SSP1) coexpressing styrene monooxygenase (SMO) and epoxide hydrolase SpEH was developed as a simple and efficient biocatalyst for S-enantioselective dihydroxylation of terminal aryl olefins 1a-15a to give (S)-vicinal diols 1c-15c in high ee (97.5-98.6% for 10 diols; 92.2-93.9% for 3 diols) and high yield (91-99% for 6 diols; 86-88% for 2 diols; 67% for 3 diols). Combining SMO and epoxide hydrolase StEH showing complementary regioselectivity to SpEH as a biocatalyst for the cascade biocatalysis gave rise to R-enantioselective dihydroxylation of aryl olefins, being the first example of this kind of reversing the overall enantioselectivity of cascade biocatalysis. E. coli (SST1) coexpressing SMO and StEH was also engineered as a green and efficient biocatalyst for R-dihydroxylation of terminal aryl olefins 1a-15a to give (R)-vicinal diols 1c-15c in high ee (94.2-98.2% for 7 diols; 84.2-89.9% for 6 diols) and high yield (90-99% for 6 diols; 85-89% for 5 diols; 65% for 1 diol). E. coli (SSP1) and E. coli (SST1) catalyzed the trans-dihydroxylation of trans-aryl olefin 16a and cis-aryl olefin 17a with excellent and complementary stereoselectivity, giving each of the four stereoisomers of 1-phenyl-1,2- propanediol 16c in high ee and de, respectively. Both strains catalyzed the trans-dihydroxylation of aryl cyclic olefins 18a and 19a to afford the same trans-cyclic diols (1R,2R)-18c and (1R,2R)-19c, respectively, in excellent ee and de. This type of cascade biocatalysis provides a tool that is complementary to Sharpless dihydroxylation, accepting cis-alkene and offering enantioselective trans-dihydroxylation.
- Wu, Shuke,Chen, Yongzheng,Xu, Yi,Li, Aitao,Xu, Qisong,Glieder, Anton,Li, Zhi
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p. 409 - 420
(2014/03/21)
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- A broadly applicable and practical oligomeric (salen)Co catalyst for enantioselective epoxide ring-opening reactions
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The (salen)Co catalyst (4a) can be prepared as a mixture of cyclic oligomers in a short, chromatography-free synthesis from inexpensive, commercially available precursors. This catalyst displays remarkable enhancements in reactivity and enantioselectivity relative to monomeric and other multimeric (salen)Co catalysts in a wide variety of enantioselective epoxide ring-opening reactions. The application of catalyst 4a is illustrated in the kinetic resolution of terminal epoxides by nucleophilic ring-opening with water, phenols, and primary alcohols; the desymmetrization of meso epoxides by addition of water and carbamates; and the desymmetrization of oxetanes by intramolecular ring opening with alcohols and phenols. The favorable solubility properties of complex 4a under the catalytic conditions facilitated mechanistic studies, allowing elucidation of the basis for the beneficial effect of oligomerization. Finally, a catalyst selection guide is provided to delineate the specific advantages of oligomeric catalyst 4a relative to (salen)Co monomer 1 for each reaction class.
- White, David E.,Tadross, Pamela M.,Lu, Zhe,Jacobsen, Eric N.
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supporting information
p. 4165 - 4180
(2014/06/09)
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- Enantioselective hydrolysis of racemic and meso -epoxides with recombinant escherichia coli expressing epoxide hydrolase from Sphingomonas sp. HXN-200: Preparation of epoxides and vicinal diols in high ee and high concentration
-
A unique epoxide hydrolase (SpEH) from Sphingomonas sp. HXN-200 was identified and cloned based on genome sequencing and expressed in Escherichia coli. The engineered E. coli (SpEH) showed the same selectivity and substrate specificity as the wild type strain and 172 times higher activity than Sphingomonas sp. HXN-200 for the hydrolysis of styrene oxide 1. Hydrolysis of racemic styrene oxide 1, substituted styrene oxides 3, 5-7, and N-phenoxycarbonyl-3,4-epoxypiperidine 8 (200-100 mM) with resting cells of E. coli (SpEH) gave (S)-epoxides 1, 3, 5-7 and (-)-8 in 98.0-99.5% enantiomeric excess (ee) and 37.6-46.5% yield. Hydrolysis of cyclopentene oxide 9, cyclohexene oxide 10, and N-benzyloxycarbonyl-3,4-epoxypyrrolidine 11 (100 mM) afforded the corresponding (R, R)-vicinal trans-diols 12-14 in 86-93% ee and 90-99% yield. The ee of (1R, 2R)-cyclohexane-1,2-diol 13 was improved to 99% by simple crystallization. These biotransformations showed high specific activity (0.28-4.3 U/mg cdw), product concentration, product/cells ratio, and cell-based productivity. Hydrolysis at even higher substrate concentration was also achieved: (S)-1 was obtained in 430 mM (51 g/Lorg) and 43% yield; (1R, 2R)-13 was obtained in 500 mM (58 g/L) and >99% yield. Gram-scale preparation of epoxides (S)-1, (S)-3, (S)-6 and diols (1R, 2R)-12, (1R, 2R)-13, (3R, 4R)-14 were also demonstrated. E. coli (SpEH) cells showed the highest enantioselectivity to produce (S)-1 (E of 39) among all known EHs in the form of whole cells or free enzymes and the highest enantioselectivities to produce (S)-3, 5, 6, 7, (-)-8, and (R, R)-14 (E of 36, 35, 28, 57, 22, and 28) among all known EHs. The easily available and highly active E. coli (SpEH) cells are the best biocatalysts known thus far for the practical preparation of these useful and valuable enantiopure epoxides and vicinal diols via hydrolysis.
- Wu, Shuke,Li, Aitao,Chin, Yit Siang,Li, Zhi
-
p. 752 - 759
(2013/06/05)
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- Retention of stereochemistry in gold-catalyzed formal [4+3] cycloaddition of epoxides with arenynamides
-
Golden opportunity: [4+3] Cycloaddition reactions of arenynamides and epoxides are enabled under gold catalysis and have a broad substrate scope (see scheme; Ms=methanesulfonyl). An SN2-type front-side attack of phenyl at the oxiranyl ring is expected to cause the retention of stereochemistry. Copyright
- Karad, Somnath Narayan,Bhunia, Sabyasachi,Liu, Rai-Shung
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supporting information; scheme or table
p. 8722 - 8726
(2012/10/18)
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- Facile and efficient hydrolysis of organic halides, epoxides, and esters with water catalyzed by ferric sulfate in a PEG1000-DAIL[BF 4]/toluene temperature-dependent biphasic system
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An efficient and environmentally friendly procedure for the hydrolysis of organic halides, epoxides, and esters with water catalyzed by ferric sulfate in a PEG1000-DAIL[BF4]/toluene temperature-dependent biphasic system has been developed. The product can be easily isolated by a simple decantation, and the catalytic system can be recycled and reused without loss of catalytic activity.
- Hu, Yu Lin,Jiang, Hui,Zhu, Jie,Lu, Ming
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experimental part
p. 292 - 298
(2011/04/21)
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- One-pot synthesis of enantiomerically pure 1, 2-diols: Asymmetric reduction of aromatic α-oxoaldehydes catalysed by Candida parapsilosis ATCC 7330
-
A facile and simple one-pot method was developed to produce a series of optically active (S)-1-phenyl-1,2-ethanediols with good yields (up to 70%) and high enantiomeric excess (>99%) via asymmetric reduction of various substituted aromatic α-oxoaldehydes using Candida parapsilosis ATCC 7330.
- Mahajabeen, Pula,Chadha, Anju
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p. 2156 - 2160
(2012/05/04)
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- Palladium-catalyzed direct oxidation of alkenes with molecular oxygen: General and practical methods for the preparation of 1, 2-diols, aldehydes, and ketones
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(Figure Presented) 1, 2-Diols, aldehydes, and ketones are important intermediates in chemical synthesis, and alkenes are possible precursors for 1, 2-diols, aldehydes, and ketones. Herein, novel and environmentally benign methods for palladium-catalyzed dihydroxylation and oxidative cleavage of olefins with oxygen as sole oxidant are presented. The cleavage reactions were performed with acid as additive in aqueous solution, whereas 1, 2-diols were formed in the presence of base. A broad substrate scope has been demonstrated allowing monosubstituted aromatic and aliphatic terminal alkenes, 1, 2-disubstituted, and 1, 1-disubstituted olefins. The cleavage reactions of dioxo-PdII complexes implicate 1, 2-diol might act as a key intermediate of olefin cleavage.
- Wang, Azhong,Jiang, Huanfeng
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supporting information; experimental part
p. 2321 - 2326
(2010/07/04)
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- A mild catalytic oxidation system: Ruthenium porphyrin and 2,6-dichloropyridine n-oxide applied for alkene dihydroxylation
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A new method was developed to transform alkenes into three types of functional molecules, including epoxides, aldehydes and 1,2-diols by using dichlororuthenium(IV) meso-tetrakis(2,6-dichlorophenyl)porphyrin [Ru(IV)(TDCPP)Cl2] as catalyst and 2,6-dichloropyridine N-oxide (Cl2pyNO) as the oxidant, in which the 1,2-diols were afforded via "one-pot" reactions in moderate yields. Copyright
- Hu, Wen-Xiang,Li, Pei-Rong,Jiang, Gaoxi,Che, Chi-Ming,Chen, Jian
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experimental part
p. 3190 - 3194
(2011/02/23)
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- Multifaceted palladium catalysts towards the tandem diboration-arylation reactions of alkenes
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Novel Pd26+ compounds have been synthesized in high yield. These compounds and their Pd24+ counterparts as synthetic precursors mediate the diboration of vinylarenes and aliphatic 1-alkenes, and under mild and basic reaction conditions they produce a variety of 1,2-diboronate esters with excellent conversions and chemo-selectivities. The presence of bis(catecholato)diboron (B2cat2) favours the reduction of PdIII to PdII, while the catalytic precursor of PdII is transformedinto Pd0-nanoparticles. An "in situ" catalytic tandem reaction has been designed to transform the diboronate intermediates into the monoarylated product, which after oxidative workup, provides the carbohydroxylated adduct. Eventually, the same catalyst performs both sequences with total conversion from the alkene.
- Penno, Dirk,Lillo, Vanesa,Koshevoy, Igor O.,Sanau, Mercedes,Ubeda, M. Angeles,Lahuerta, Pascual,Fernandez, Elena
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supporting information; experimental part
p. 10648 - 10655
(2009/12/01)
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- Asymmetric hydrogenation of α-hydroxy ketones catalyzed by MsDPEN-Cp*Ir(III) complex
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Asymmetric hydrogenation of a series of α-hydroxy aromatic ketones in methanol catalyzed by Cp*Ir(OTf)(MsDPEN) (MsDPEN = N-(methanesulfonyl)-1, 2-diphenylethylenediamine) affords the 1-aryl-1,2-ethanediols in up to 99% ee. The reaction can be conducted with a substrate-to-catalyst molar ratio at high as 6000 under 10 atm of H2-1-Hydroxy-2-propanone is also hydrogenated with high enantioselectivity.
- Ohkuma, Takeshi,Utsumi, Noriyuki,Watanabe, Masahito,Tsutsumi, Kunihiko,Arai, Noriyoshi,Murata, Kunihiko
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p. 2564 - 2567
(2008/02/05)
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- New mono-quarternized bis-Cinchona alkaloid ligands for asymmetric dihydroxylation of olefins in aqueous medium: Unprecedented high enantioselectivity and recyclability
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New mono-quaternized allyl bromide salts of bis-Cinchona alkaloid ligands, [(QD)2PHAL-Allyl]Br and [(QN)2PHAL-Allyl]Br, have been synthesized which can be converted into their highly water-soluble multihydroxylated derivatives under asymmetric dihydroxylation (AD) conditions and, thus, easily recovered by a simple extraction method after reaction and reused. These mono-quaternized ligands exhibited superior catalytic efficiency to their neutral counterparts such as (DHQD)2PHAL and (DHQ) 2PHAL for the AD reactions of mono- and disubstituted styrenes under Upjohn conditions. Merely 0.1 mol% of osmium was enough to complete the reactions of mono- and disubstituted styrenes and, moreover, these ligands showed the highest enantioselectivities (e.g., for styrene, 97% ee with [(QD)2PHAL-Allyl]Br) among those ever achieved under Upjohn conditions. Wiley-VCH Verlag GmbH & Co. KGaA.
- Choi, Doo Seung,Han, Sang Seop,Kwueon, Eun Kyung,Choi, Han Young,Hwang, Soon Ho,Park, Yil Sung,Song, Choong Eui
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p. 2560 - 2564
(2007/10/03)
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- Coinage metal complexes with N-heterocyclic carbene ligands as selective catalysts in diboration reaction
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We describe the improved catalytic reactivity of terminal alkenes with 1,2-diboranes in the presence of Au(I) and Ag(I) complexes when N-heterocyclic carbene ligands are used. The new catalytic systems are able to diminish the undesired β-H-elimination of the alkylboryl-metal intermediates, which leads to the formation of hydroborated byproducts. The electronic properties and molecular the structure of the precursors of the catalysts could explain the modest asymmetric induction provided.
- Corberan, Rosa,Ramirez, Jesus,Poyatos, Macarena,Peris, Eduardo,Fernandez, Elena
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p. 1759 - 1762
(2007/10/03)
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- 2,4-DIAMINOQUINAZOLINES FOR SPINAL MUSCULAR ATROPHY
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2,4-Diaminoquinazolines of formulae I-IV and VI (I, II, III, IV and VI) are useful for treating spinal muscular atrophy (SMA).
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Page/Page column 94
(2010/02/15)
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- Unprecedented use of silver(I) N-heterocyclic carbene complexes for the catalytic preparation of 1,2-bis(boronate) esters
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Catalytic diboration of internal and terminal alkenes with Ag(I) N-heterocyclic carbene complexes leads to 1,2-bis(boronate) esters as single intermediates, that can be oxidised towards the corresponding diols. The Royal Society of Chemistry 2005.
- Ramirez, Jesus,Corberan, Rosa,Sanau, Mercedes,Peris, Eduardo,Fernandez, Elena
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p. 3056 - 3058
(2007/10/03)
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- Catalytic enantioselective hydrogenation of vinyl bis(boronates)
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Catalytic enantioselective hydrogenation of prochiral vinylmetallic reagents can provide an attractive alternative to hydrometalation and bismetalation of alkenes. In this contribution, the first highly enantioselective hydrogenation of vinyl boronic esters is described. The chiral reduction products are versatile intermediates for chemical synthesis. Copyright
- Morgan, Jeremy B.,Morken, James P.
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p. 15338 - 15339
(2007/10/03)
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- Enantioselective reduction of α-keto esters to 1,2-diols using the NaBH4/Me3SiCl system catalyzed by polymer-supported chiral sulfonamide
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In the presence of 25mol% of a polymer-supported chiral sulfonamide, a variety of α-keto esters can be reduced into the corresponding 1,2-diols in good yields and high enantioselectivities using the NaBH4/Me 3SiCl reducing system.
- Wang, Guang-Yin,Hu, Jian-Bing,Zhao, Gang
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p. 807 - 810
(2007/10/03)
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- Enantioselective hydrolysis of various substituted styrene oxides with Aspergillus Niger CGMCC 0496
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Enantioselective biohydrolysis of various substituted styrene oxides using whole fungus cells of Aspergillus niger CGMCC 0496 are described. The results show not only para- but also some ortho- substituted styrene oxides can achieve high enantioselectivity during the hydrolysis.
- Jin, Hao,Li, Zu-Yi,Dong, Xiao-Wei
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p. 408 - 414
(2007/10/03)
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- New uses for the Burgess reagent in chemical synthesis: Methods for the facile and stereoselective formation of sulfamidates, glycosylamines, and sulfamides
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Although the Burgess reagent (methoxycarbonylsulfamoyltriethylammonium hydroxide, inner salt) has found significant use in chemical synthesis as a dehydrating agent, almost no work has been directed towards its potential in other synthetic applications. As this article will detail, we have found that the Burgess reagent is remarkably effective at accomplishing a number of non-dehydrative synthetic tasks when applied to appropriate substrates, such as the formation of sulfamidates from 1,2-diols or epoxyalcohols, α- and β-glycosylamines from carbohydrates, and cyclic sulfamides from 1,2-aminoalcohols. Beyond delineating the power of these new reaction manifolds, we also describe the construction of a group of alternative Burgess-type reagents that extends the scope of these new reactions even further.
- Nicolaou,Snyder, Scott A.,Longbottom, Deborah A.,Nalbandian, Annie Z.,Huang, Xianhai
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p. 5581 - 5606
(2007/10/03)
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- Stereoselective synthesis of styrene oxides via a Mitsunobu cyclodehydration.
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[reaction: see text] The Mitsunobu cyclodehydration of chiral phenethane-1,2-diols (4), readily accessed from the styrene derivative (5), has been demonstrated to provide the corresponding styrene oxides (2) with high levels of stereoretention (up to 99%). Optimized reaction conditions are described, from which the combination of tricyclohexylphosphine (Chx(3)P) and diisopropylazodicarboxylate (DIAD) in THF and R = EWG provides the best results.
- Weissman,Rossen,Reider
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p. 2513 - 2515
(2007/10/03)
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- Stereoelectronic effects in the DIBAL reduction of aryl-1,2-ethanediol benzylidene acetals
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Reduction of benzylidene acetal 8 with DIBAL-H selectively gave 4 in 89% yield. 1-Aryl-1,2-diol benzylidene acetals display unusual regioselectivity with electron withdrawing groups on the aryl group.
- Gauthier Jr., Donald R,Szumigala Jr., Ronald H,Armstrong III, Joseph D,Volante
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p. 7011 - 7014
(2007/10/03)
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- Microbiological Transformations. 38. Clues to the Involvement of a General Acid Activation during Hydrolysis of Para-Substituted Styrene Oxides by a Soluble Epoxide Hydrolase from Syncephalastrum racemosum
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In the course of this work, we have determined the regioselectivity as well as the rate of biohydrolysis of various para-substituted styrene oxide derivatives catalyzed by a new epoxide hydrolase activity found in the soluble cell extract of the fungus Syncephalastrum racemosum. We have observed that this regioselectivity switched progressively from the benzylic Cα carbon atom to the terminal Cβ carbon atom depending upon the electronic character of the para substituent. Hammett plotting of the ratio of water incorporation at both the benzylic and terminal carbon atoms, i.e., log α/β versus σ, gave linear relationships for the two (R)- and (S)-epoxide enantiomers with slopes pα/β = -2.07 and -1.35, respectively. Apparent kinetic constants Km and Vmax were determined for the biohydrolysis of the enantiomers of R absolute configuration, which were the better substrates. Hammett correlation was investigated for Vmax/Km for the reaction on both the Cα and Cβ carbon atoms. Log αVmax/Km vs σ gave a linear relationship with a slope pαvmax/Km = -1.8, suggesting that, in the case of these enzyme/substrate couples, the rate-determining step is the oxirane ring cleavage. These results give, for the first time, interesting clues to the fact that a general acid activation of the epoxide is very probably involved in a concerted process together with its nucleophilic attack.
- Moussou,Archelas,Baratti,Furstoss
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p. 3532 - 3537
(2007/10/03)
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- Microbiological transformations. 33. Fungal epoxide hydrolases applied to the synthesis of enantiopure para-substituted styrene oxides. A mechanistic approach
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The biohydrolysis of differently para-substituted styrene oxide derivatives was studied, using whole cells of the fungi Aspergillus niger or Beauveria sulfurescens. These microorganisms proved to be equipped with epoxide hydrolases which are able to achieve these hydrolyses with high enantioselectivity. This allowed the preparation of the optically active epoxides and of the corresponding vicinal diols which were obtained with good to excellent enantiomeric purity. These two microorganisms proved to be enantiocomplementary. A mechanistic study, carried out using a crude lyophilized enzymatic extract from A. niger, indicated via Hammet coefficient plotting that this hydrolysis is very probably due to a general base-catalyzed process.
- Pedragosa-Moreau,Morisseau,Zylber,Archelas,Baratti,Furstoss
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p. 7402 - 7407
(2007/10/03)
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